JP2011209056A - Gnss receiving device and positioning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a positioning rate, while reducing an influence of multipath.SOLUTION: This GNSS (Global Navigation Satellite System) receiving device includes: a first correlation peak detection part for detecting a correlation peak; a second correlation peak detection part for detecting a correlation peak by a multipath error reduction technology; a signal intensity detection part for detecting positioning signal intensity; a switching part for inputting a positioning signal into the first or second correlation peak detection part; a signal intensity determination part for performing instruction for inputting the positioning signal into the second correlation peak detection part, when the signal intensity is higher than a threshold, and for inputting it into the first correlation peak detection part, when the signal intensity is lower than the threshold; a multipath determination part for determining whether the positioning signal is affected by the multipath or not; a timing control part for performing instruction for inputting the positioning signal into the first correlation peak detection part, when detection of the correlation peak by the multipath error reduction technology cannot be continued for a prescribed time; and a positioning operation part for calculating a pseudo distance based on the correlation peak, and calculating the position.

Description

  The present invention relates to a GNSS receiver and a positioning method for receiving and positioning a signal from a GNSS orbiting satellite.

  The Global Navigation Satellite System (GNSS) is a system that obtains the distance from each GNSS satellite by capturing three navigation satellites (GNSS orbiting satellites) (hereinafter referred to as GNSS satellites) from the aircraft. It is a navigation system that can obtain the flight position in three dimensions of the aircraft by adjusting the time with the signal from the eye navigation satellite. Satellite navigation includes the Global Positioning System (GPS), Galileo, and others.

  For example, the GNSS receiver is mounted on a moving body and measures the position and speed of the moving body. For example, the GNSS receiver receives radio waves from a plurality of GNSS satellites, calculates the distances (pseudo distances) from the plurality of GNSS satellites to the GNSS receiver, and receives the GNSS reception based on the pseudo distances. Measures the moving object equipped with the device. The signal emitted by the GNSS satellite arrives at the GNSS receiver with a delay in the distance between the GNSS satellite and the GNSS receiver by the time the radio wave propagates. Therefore, if the time required for radio wave propagation is obtained for a plurality of GNSS satellites, the position of the GNSS receiver can be obtained by positioning calculation. For example, for a radio wave emitted by a plurality of GNSS satellites, a pseudo distance from each GNSS satellite to the GNSS receiver is obtained in a pseudo distance calculator of the GNSS receiver. Then, the positioning calculation unit obtains the position of the GNSS receiver based on the pseudo distance obtained by the pseudo distance calculation unit.

  The GNSS receiver detects a correlation peak by acquiring a correlation between a signal received from the GNSS satellite and a C / A code replica signal after capturing the GNSS satellite. For example, by adjusting the phase of the C / A code replica signal, the correlation peak with the signal received from the GNSS satellite is obtained. The GNSS receiver obtains a pseudo distance between the GNSS satellite and the GNSS satellite from the phase delay amount of the correlation peak. Based on the pseudorange, the position of the GNSS receiver is obtained.

  However, even when a GNSS receiver can capture a GNSS satellite, it may receive not only the direct wave from the GNSS satellite but also a radio wave reflected and diffracted by a building such as a high-rise building. The phenomenon in which radio waves transmitted from GNSS satellites are reflected and diffracted and received from multiple propagation paths is also called multipath. Due to the multipath effect, an error occurs in the pseudorange between the GNSS receiver and the GNSS satellite. A positioning error occurs due to an error in the pseudorange.

JP 2008-070338 A

  One of the causes of positioning errors in the GNSS receiver is the effect of multipath. One method for reducing the influence of the multipath is to use a multipath error reduction technique such as a narrow-correlator. By using the multipath error reduction technique, it is possible to reduce errors occurring in the pseudorange. Since errors occurring in the pseudo distance can be reduced, positioning errors can be reduced.

  FIG. 1 shows an example of a GNSS receiver.

  Radio waves from the GNSS satellite are input to the high frequency processing unit 2 from the antenna. The high frequency processing unit 2 processes a high frequency analog signal input by an antenna. The satellite capturing unit 4 captures a GNSS satellite based on the signal processed by the high frequency processing unit 2. The correlator unit 6 detects a correlation peak by obtaining a correlation between the received signal from the GNSS satellite captured by the satellite capturing unit 4 and the C / A code replica signal.

  FIG. 2 shows an example of processing by the correlator unit 6. In FIG. 2, the horizontal axis is the chip, and the vertical axis is the signal intensity level of the correlation value.

  For example, in the correlator, the width between early and late (hereinafter referred to as “spacing”) is one chip, and tracking is performed so that the difference between the signal intensity levels of both correlation values becomes zero. In FIG. 2, phase control is performed so that the signal intensity levels (indicated by 0.5E and 0.5L) of the correlation values at both ends of the spacing by one chip are equal. The center of the spacing is a tracking point. The phase of the replica signal of the C / A code is adjusted so that the tracking point becomes maximum, and the maximum value P (referred to as “correlation peak”) of the tracking point is obtained. When affected by multipath, the maximum value of the tracking point may be shifted toward early or late.

  In order to reduce the influence of multipath, after the tracking, the spacing is narrowed, and the signal strength level (NE, NL) of the correlation value at the chip closer to the chip corresponding to the correlation peak obtained by the spacing by one chip. (Shown by). Phase control is performed so that NE and NL are equal. The center of the spacing is a tracking point. The correlation peak is obtained by adjusting the phase of the C / A code replica signal so that the tracking point is maximized.

  The pseudo distance calculation unit 8 obtains a pseudo distance between the GNSS receiver and the GNSS satellite based on the phase delay amount of the correlation peak detected when the spacing is narrowed by the correlator unit 6.

  When narrowing the spacing and determining the signal intensity level of the correlation value at the chip closer to the chip corresponding to the correlation peak obtained by spacing by one chip, the phase is controlled because NE and NL are close to the correlation peak. However, the fluctuation of the correlation value due to the phase control is small. Since the correlation value fluctuation due to phase control is small, the level of the received signal of the radio wave from the GNSS satellite is low, and when the influence of noise becomes large, the received signal level of noise will be higher than NE and NL. There is. When the received signal level of noise is higher than NE and NL, the correlation value at the chip closer to the chip corresponding to the correlation peak obtained by spacing by one chip is obtained even if the spacing is narrowed. I can't. If the correlation value cannot be obtained, the tracked GNSS satellite may be removed. When the satellite tracking is removed, it is necessary to perform the processing from the satellite capture again, and positioning may not be performed during the satellite capture. Positioning rate decreases because positioning is not possible.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a GNSS receiver and a positioning method capable of improving the positioning rate while reducing the influence of multipath.

This GNSS receiver
A GNSS receiver that performs a positioning operation based on a positioning signal transmitted from a GNSS satellite,
A first correlation peak detector for detecting a peak of a correlation value between the positioning signal and a C / A code replica signal;
A second correlation peak detector for detecting a peak of a correlation value between the positioning signal and the C / A code replica signal by a multipath error reduction technique;
A signal strength detector for detecting the signal strength of the positioning signal;
A switching unit that switches an input destination of the positioning signal between the first correlation peak detection unit and the second correlation peak detection unit;
The switching unit is instructed to input to the second correlation peak detection unit when the signal intensity is equal to or higher than a predetermined threshold, and when the signal intensity is lower than the predetermined threshold, the positioning signal is transmitted to the first correlation signal. A signal intensity level determination unit that gives an instruction to input to the correlation peak detection unit of
A multipath determination unit that determines whether the positioning signal is affected by a multipath based on a correlation value to be detected by the second correlation peak detection unit;
Based on the correlation value to be detected by the second correlation peak detection unit when the positioning signal is determined to be affected by the multipath by the multipath determination unit, the second correlation peak A phase control determination unit that determines whether or not the detection unit can continue to detect the peak of the correlation value;
A timing control unit that instructs the switching unit to input the positioning signal to the first correlation peak detection unit when it is determined by the phase control determination unit that it cannot be continued;
A positioning calculation unit that calculates a pseudo distance based on the correlation peak detected by the first correlation peak detection unit or the second correlation peak detection unit, and calculates a position based on the pseudo distance. .

This positioning method is
A positioning method in a GNSS receiver that performs a positioning operation based on a positioning signal transmitted from a GNSS satellite,
A first correlation peak detecting step for detecting a peak of a correlation value between the positioning signal and a C / A code replica signal;
A second correlation peak detecting step for detecting a peak of a correlation value between the positioning signal and the C / A code replica signal by a multipath error reduction technique;
A signal strength detection step of detecting a signal strength of the positioning signal;
A switching step of switching between the first correlation peak detection step and the second correlation peak detection step;
A signal strength level determination step that switches to the second correlation peak detection step when the signal strength is equal to or greater than a predetermined threshold, and that switches to the first correlation peak detection step when the signal strength is less than the predetermined threshold;
A multipath determination step of determining whether or not the positioning signal is affected by a multipath based on the correlation value to be detected by the second correlation peak detection step;
When it is determined in the multipath determination step that the positioning signal is affected by the multipath, the second correlation peak is determined based on the correlation value to be detected in the second correlation peak detection step. A phase control determination step for determining whether the detection step can continue to detect the peak of the correlation value;
A timing control step for instructing to switch to the first correlation peak detection step when it is determined that the phase control determination step cannot continue,
A positioning calculation step of calculating a pseudo distance based on the correlation peak detected by the first correlation peak detection step or the second correlation peak detection step and calculating a position based on the pseudo distance. .

  According to the disclosed GNSS receiver and positioning method, it is possible to improve the positioning rate while reducing the influence of multipath.

It is an example of the functional block diagram of a GNSS receiver. It is explanatory drawing which shows an example of the correlation detection between a positioning signal and the replica signal of a C / A code. It is explanatory drawing which shows the electromagnetic wave received by the GNSS receiver according to a present Example. It is explanatory drawing (the 1) which shows the error of the correlation peak by the influence of multipath. It is explanatory drawing (the 2) which shows the error of the correlation peak by the influence of multipath. It is explanatory drawing which shows an example of the correlation detection between the replica signals of the C / A code | cord | chord by the difference in the signal strength level of a positioning signal. It is explanatory drawing which shows an example of the correlation detection between the replica signals of a C / A code when the signal strength level of a positioning signal is low. It is a functional block diagram which shows the GNSS receiver according to a present Example. It is explanatory drawing which shows the determination example of the multipath in the GNSS receiver according to a present Example, and the determination example of the fading level of a reflected wave. It is a flowchart which shows an example of operation | movement of the GNSS receiver according to a present Example. It is a functional block diagram which shows the GNSS receiver according to a present Example. It is explanatory drawing which shows the threshold value of the correlation value in the GNSS receiver according to a present Example.

Next, the best mode for carrying out the present invention will be described based on the following embodiments with reference to the drawings.
In all the drawings for explaining the embodiments, the same reference numerals are used for those having the same function, and repeated explanation is omitted.
<Example>
<System>
A global navigation satellite system (GNSS) according to this embodiment includes a GNSS satellite that orbits the earth and a GNSS receiver 100 that is located on the earth and can move on the earth. In this embodiment, GPS will be described as an example of GNSS. You may apply to GNSS other than GPS.

  GNSS satellites always broadcast navigation messages (satellite signals) to the earth. The navigation message includes satellite orbit information (ephemeris and almanac) for the corresponding GNSS satellite, clock correction values, and ionospheric correction coefficients. The navigation message is spread by the C / A code, placed on the L1 band carrier (frequency: 1575.42 MHz), and constantly broadcast toward the earth. In addition, the navigation message is spread by the P code, and is always broadcast to the earth on the L2 band carrier (frequency: 1227.6 MHz).

  The L1 band carrier wave is a combined wave of a sine wave modulated with a C / A code and a Cos wave modulated with a P code (Precision Code), and is orthogonally modulated. The L2 band carrier wave is a Cos wave modulated with a P code and is orthogonally modulated. The C / A code and the P code are pseudo noise codes, and are code strings in which -1 and 1 are arranged irregularly and periodically.

  Currently, about 30 GNSS satellites orbit the earth at an altitude of about 20,000 km, and there are six orbiting planes inclined by 55 degrees, each with four or more GNSS satellites. Are evenly arranged. Therefore, at least 5 or more GNSS satellites can be observed at any time anywhere on the earth as long as the sky is open.

<GNSS receiver>
The GNSS receiver 100 is mounted on a mobile object, for example. The mobile body includes a vehicle, a motorcycle, a train, a ship, an aircraft, a robot, and the like, and an information terminal such as a portable terminal that moves as a person moves. In the present embodiment, a case where it is mounted on a vehicle will be described as an example of a moving body.

  FIG. 3 shows radio waves received by the GNSS receiver 100. A signal received by the GNSS receiver 100 may be affected by multipath. Specifically, the GNSS receiving apparatus 100 simultaneously receives a direct wave that can be directly received from a GNSS satellite and a reflected wave that is received when a radio wave emitted from the GNSS satellite is reflected by a building or the like. When the direct wave and the reflected wave are received simultaneously, the correlation waveform between the received signal and the C / A code replica signal is the same as the correlation waveform between the direct wave and the C / A code replica signal, This is a waveform obtained by synthesizing the correlation waveform between the wave and the C / A code replica signal.

<Example of tracking by correlator>
4 and 5 show examples of tracking by the correlator when the direct wave and the reflected wave are received in the same phase and when they are received in the opposite phase. 4 and 5, the horizontal axis is the chip, and the vertical axis is the signal intensity level of the correlation value.

<When direct wave and reflected wave are received in phase>
FIG. 4 shows a case where the direct wave and the reflected wave are received in the same phase. FIG. 4 shows two examples of spacing as an example.

  When wide spacing, for example, spacing is 1 chip, the phase control of the C / A code replica signal is performed so that, for example, 0.5E = 0.5L. According to FIG. 4, the chip position corresponding to the correlation peak obtained from the correlation waveform between the received signal including the direct wave and the reflected wave and the replica signal of the C / A code is determined by the direct wave and the C / A code. In this direction, the phase lags behind the chip position corresponding to the correlation peak obtained from the correlation waveform with the replica signal. That is, an error occurs in the direction in which the code phase is delayed. Since an error occurs in the direction in which the code phase is delayed, the pseudorange is calculated to be long.

  When the narrow spacing, for example, the spacing is 0.1 chip, the phase control of the C / A code replica signal is performed so that NE = NL. The chip position corresponding to the correlation peak obtained by the correlation waveform between the received signal including the direct wave and the reflected wave and the C / A code replica signal is between the direct wave and the C / A code replica signal. This is a direction in which the phase lags behind the chip position corresponding to the correlation peak obtained from the correlation waveform. This is the same as in the case of wide spacing. However, in the case of narrow spacing, it corresponds to the correlation peak obtained by the correlation waveform between the received signal including the direct wave and reflected wave and the replica signal of the C / A code than in the case of wide spacing. The difference between the chip position corresponding to the correlation peak obtained by the correlation waveform between the direct wave and the C / A code replica signal is small. This is because when the spacing is narrower, phase control is performed at a chip closer to the correlation peak. Since the difference is small, the phase delay error of the correlation peak is small. Since the phase delay error of the correlation peak becomes small, a pseudo distance closer to the pseudo distance obtained by the direct wave can be obtained when the spacing is narrow. In other words, the influence of multipath can be reduced.

<When direct wave and reflected wave are received in opposite phases>
FIG. 5 shows a case where the direct wave and the reflected wave are received in opposite phases. FIG. 5 shows two examples of spacing as an example. When wide spacing, for example, spacing is 1 chip, the phase control of the C / A code replica signal is performed so that, for example, 0.5E = 0.5L. According to FIG. 5, the chip position corresponding to the correlation peak obtained by the correlation waveform between the received signal including the direct wave and the reflected wave and the replica signal of the C / A code is the direct wave and the C / A code. This is the direction in which the phase advances from the chip position corresponding to the correlation peak obtained from the correlation waveform with the replica signal. That is, an error occurs in the direction in which the code phase advances. Since an error occurs in the direction in which the code phase advances, the pseudorange is calculated to be short. When narrow spacing, for example, the spacing is 0.1 chip, phase control of the C / A code replica signal is performed so that NE = NL. The chip position corresponding to the correlation peak obtained by the correlation waveform between the received signal including the direct wave and the reflected wave and the C / A code replica signal is between the direct wave and the C / A code replica signal. The phase advances from the chip position corresponding to the correlation peak obtained from the correlation waveform. This is the same as in the case of wide spacing. However, in the case of narrow spacing, it corresponds to the correlation peak obtained by the correlation waveform between the received signal including the direct wave and reflected wave and the replica signal of the C / A code than in the case of wide spacing. The difference between the chip position corresponding to the correlation peak obtained by the correlation waveform between the direct wave and the C / A code replica signal is small. This is because when the spacing is narrower, phase control is performed at a chip closer to the correlation peak. Since the difference is small, the phase delay error of the correlation peak is small. Since the phase delay error of the correlation peak becomes small, a pseudo distance closer to the pseudo distance obtained by the direct wave can be obtained when the spacing is narrow. In other words, the influence of multipath can be reduced.

  In addition, when a mobile body and / or a GNSS satellite on which the GNSS receiver 100 is mounted move with respect to a wall, the path difference between the direct wave and the reflected wave changes with time. As the path difference between the direct wave and the reflected wave changes, the phase of the reflected wave also changes. As the phase of the reflected wave changes, the error included in the pseudorange also fluctuates around the true value. The path difference is a difference between the direct wave path directly coming from the GNSS satellite to the GNSS receiver 100 and the reflected wave path reflected from the GNSS satellite by a building or the like. For example, one period of the phase of the reflected wave corresponds to about 20 cm. Therefore, every time the path difference increases or decreases by about 20 cm, the change between the correlation waveform shown in FIG. 4 and the correlation waveform shown in FIG. 5 is repeated. Specifically, when a moving body moves vertically on a wall at a speed of 40 km / h, the speed of 40 km / h is approximately 11 m / s, so that the correlation shown in FIG. 4 is 110 times per second from 11 m / 0.2 m × 2 = 110. The change between the waveform and the correlation waveform shown in FIG. 5 is repeated. As a result of repeating this change, the pseudorange varies.

  When the speed of the moving body is high, such as during normal driving, the change between the correlation waveform shown in FIG. 4 and the correlation waveform shown in FIG. 5 is repeated quickly, so that the correlation peak to be obtained from the correlation waveform is obtained. Corresponding chip positions are time averaged. An error occurs in the direction in which the code phase is delayed from the correlation waveform shown in FIG. 4, and an error occurs in the direction in which the code phase advances from the correlation waveform shown in FIG. A chip position substantially similar to the chip position corresponding to the correlation peak obtained from the correlation waveform between the direct wave and the C / A code replica signal is obtained.

  However, when the speed of the moving body is low or when the vehicle is stopped, the change between the correlation waveform shown in FIG. 4 and the correlation waveform shown in FIG. 5 is slow. Since the change is slow, even if the chip position corresponding to the correlation peak to be obtained by the correlation waveform is time-averaged, it corresponds to the correlation peak obtained by the correlation waveform between the direct wave and the C / A code replica signal. The chip position to be obtained cannot be obtained.

  Further, for example, in the example shown in FIG. 5, if only a direct wave is used, phase control can be performed with narrow spacing. However, when the direct wave and a reflected wave having a phase opposite to that of the direct wave are combined, the signal intensity of the combined wave decreases. Since the signal strength decreases, the phase control of the C / A code replica signal may be impossible due to the narrow spacing.

<When signal strength level from GNSS satellite is low>
A case where the signal strength level from the GNSS satellite is low will be described.

  FIG. 6 shows a comparison of correlation waveforms when the signal strength level from the GNSS satellite is high and low. FIG. 6 shows an example of a correlation waveform of a direct wave as an example. However, the same is true even if a reflected wave is included.

  When the signal strength level is high, a correlation peak is obtained regardless of the width of the spacing. On the other hand, when the signal strength level is low, it is possible to obtain a correlation peak by controlling the phase of the C / A code replica signal in the case of wide spacing, but in the case of narrow spacing Even if the phase of the C / A code replica signal is adjusted, a correlation peak may not be obtained. This is because a received signal including a direct wave and a reflected wave may be buried in noise.

  FIG. 7 is an enlarged view of the correlation waveform when the signal intensity level is low. When the signal intensity level is low, the influence of noise becomes large. Since the influence of noise increases, in the case of narrow spacing, even if phase control is performed so that NE and NL are equal, a correlation peak may not be obtained. This is because a received signal including a direct wave and a reflected wave may be buried in noise. In the example shown in FIG. 7, an example in which NL is larger than the correlation peak is shown. Even if NE and NL phase control are performed, the tracking GNSS satellite may be removed because the correlation peak cannot be obtained. If the tracked GNSS satellite is removed, it will be necessary to start from capturing the satellite again. This is because once the process shifts to phase control of the C / A code replica signal by narrow spacing, it cannot return to the process of phase control of the C / A code replica signal by wide spacing. .

  The GNSS receiver 100 observes the signal strength level of the correlation value between the received signal and the C / A code replica signal. The GNSS receiver 100 performs phase control of a C / A code replica signal with a wide spacing after acquiring a GNSS satellite. For example, the phase of the C / A code replica signal is controlled so that 0.5E = 0.5L by spacing of one chip. When the phase of the C / A code replica signal is controlled by the wide spacing, the signal intensity level of the received signal is observed.

  The GNSS receiver 100 determines whether the signal strength level of the received signal is equal to or higher than a preset signal strength level. When it is determined from the determination result that the signal strength level of the received signal is equal to or higher than a preset level, the multipath error is reduced by a multipath error reduction technique. The multipath error reduction technology includes a narrow correlator, an early-late slope, a strobe correlator, a multipath estimation delay-lock loop (MEDLL). ) Is included. In the present embodiment, a case where a narrow correlator is applied will be described as an example, but other multipath error reduction techniques may be applied as described above. In this embodiment, the signal strength level of the correlation value between the received signal and the C / A code replica signal is used as the signal strength level of the received signal. When it is determined that the signal intensity level of the correlation value is equal to or higher than a preset signal intensity level, the multipath error is reduced by a multipath error reduction technique. Other values may be used instead of the signal strength level of the received signal, and it may be determined whether or not to reduce the multipath error by the multipath error reduction technique. For example, reception SINR and S / N may be used.

  The GNSS receiver 100 obtains a correlation peak with a wide spacing and then performs phase control of a C / A code replica signal with a narrow spacing. For example, the GNSS receiving apparatus 100 obtains a correlation peak by spacing by one chip as a wide spacing, and then obtains a signal intensity level of a correlation value at a chip closer to the chip corresponding to the correlation peak by narrow spacing. This GNSS receiver 100 performs phase control so that NE and NL are equal. The center of the spacing is a tracking point. The correlation peak is obtained by adjusting the phase of the C / A code replica signal so that the tracking point is maximized.

  The GNSS receiver 100 determines whether or not the received signal is affected by multipath while performing phase control of the replica signal of the C / A code by the narrow spacing. For example, the determination may be made for each epoch, for example, with one epoch as a unit. If it is determined by the determination that the received signal is affected by multipath, the signal intensity level of the correlation value is less than the signal intensity level at which the phase control of the C / A code replica signal can be performed by narrow spacing. In other words, it is determined whether it can continue for a predetermined time. The correlation waveform between the received signal and the C / A code replica signal periodically changes between the correlation waveform shown in FIG. 4 and the correlation waveform shown in FIG. Therefore, the correlation waveform shown in FIG. 5 is obtained periodically. In the correlation waveform shown in FIG. 5, the signal intensity level of the synthesized wave is lower than the signal intensity level of the direct wave. If the signal intensity level of the synthesized wave is lower than the signal intensity level of the direct wave, the phase control of the C / A code replica signal may not be performed due to the narrow spacing.

  When it is determined that the signal strength level is such that the phase control of the C / A code replica signal cannot be performed due to the narrow spacing, the GNSS receiver 100 controls the phase of the C / A code replica signal due to the narrow spacing. Controls the phase of the C / A code replica signal with wide spacing when the signal intensity level that can be used is obtained and the phase of the reflected wave is 90 degrees away from the direct wave Switch to processing. In other words, the GNSS receiver 100 is capable of obtaining a signal intensity level capable of performing the phase control of the C / A code replica signal with a narrow spacing and without being affected by the reflected wave. Then, the processing is switched to the phase control of the C / A code replica signal by wide spacing.

  For example, when the correlation signal strength level is less than the signal strength level that allows the phase control of the C / A code replica signal due to narrow spacing, the C / A code replica signal is When the phase control is performed, the phase control of the C / A code replica signal is performed so that 0.5E is equal to 0.5L. However, in the situation where the correlation waveform shown in FIG. 5 is obtained, the difference between 0.5E and 0.5L is large. Since the difference between 0.5E and 0.5L is large, in order to control the phase of the replica signal of the C / A code so that 0.5E and 0.5L are equal, an attempt is made to pull back the phase. , It takes time to make 0.5L equal. In some cases, the tracking satellite may be removed. If the tracked satellite is removed, it must be repeated from satellite capture.

  In this GNSS receiver 100, while performing phase control of a C / A code replica signal with narrow spacing, it is determined that the received signal is affected by multipath, and the signal strength level of the correlation value is narrow. When it is determined that the signal strength level is likely to be less than the signal strength level at which the phase control of the C / A code replica signal can be performed by spacing, in other words, when it is determined that the predetermined time cannot be continued, Due to the wide spacing when the signal intensity level that can control the phase of the C / A code replica signal is obtained by pacing and when the phase of the reflected wave is shifted by 90 degrees from the direct wave Controls the phase of the C / A code replica signal and switches to processing for obtaining a correlation peak. While a signal intensity level that can control the phase of a C / A code replica signal with narrow spacing is obtained, and when the phase of the reflected wave is shifted by 90 degrees with respect to the direct wave, a wide scan is performed. In order to control the phase of the C / A code replica signal by pacing and switch to the processing to obtain the correlation peak, the phase control of the C / A code replica signal is performed by narrow spacing with respect to the correlation waveform shown in FIG. The correlation peak can be continuously obtained without removing the satellite tracking assumed to be caused by obtaining the correlation peak. In particular, when the speed of the moving body is low, or when the moving body is stopped, the change between the correlation waveform shown in FIG. 4 and the correlation waveform shown in FIG. It is assumed that the phase of the C / A code replica signal is controlled by narrow spacing with respect to the correlation waveform, and the processing to obtain the correlation peak is performed, which increases the probability of removing the captured satellite. Is done. Therefore, when the speed of the moving body is low, there is a great advantage that the captured satellite is not removed when the moving body is stopped. As a result of removing the tracking GNSS satellite, the positioning rate can be improved. This is because the processing is not performed again from capturing the satellite.

<This GNSS receiver>
FIG. 8 shows the present GNSS receiver.

  The GNSS receiver 100 has an antenna 102. The antenna 102 receives radio waves transmitted by GNSS satellites. The radio wave received by the antenna 102 is input to the high frequency processing unit 104 as a high frequency signal.

  The GNSS receiver 100 includes a high frequency processing unit 104. The high frequency processing unit 104 is connected to the antenna 102. The high-frequency processing unit 104 converts a high-frequency signal from the antenna 102 into an intermediate frequency signal. The intermediate frequency signal is input to the satellite acquisition unit 106.

  The GNSS receiver 100 includes a satellite capturing unit 106. The satellite capturing unit 106 is connected to the high frequency processing unit 104. The satellite capturing unit 106 captures a GNSS satellite based on the intermediate frequency signal input by the high frequency processing unit 104.

  The GNSS receiver 100 has a switching unit 108. The switching unit 108 is connected to the satellite capturing unit 106. The switching unit 108 switches the input destination of the intermediate frequency signal from the GNSS satellite captured by the satellite capturing unit 106.

  The GNSS receiver 100 includes a multipath error reduction unit 110. The multipath error reduction unit 110 is connected to the switching unit 108. The multipath error reduction unit 110 detects a correlation peak by obtaining a correlation between the intermediate frequency signal to be input by the switching unit 108 and the C / A code replica signal. The chip width of the spacing to be used when detecting the correlation peak is switched according to the signal intensity level of the correlation peak. For example, when the correlation peak is equal to or greater than a predetermined correlation value threshold value, the process is switched from the process of obtaining the correlation peak by wide spacing to the process of obtaining the correlation peak by narrow spacing. Further, while the processing for obtaining the correlation peak by narrow spacing is performed, it is determined that the received signal is affected by multipath, and the signal strength level of the correlation value is C / A by narrow spacing. Perform phase control of the code replica signal, and if it is determined that the signal intensity level is likely to be less than the signal intensity level at which the correlation peak can be obtained, perform phase control of the C / A code replica signal with narrow spacing, When the correlation peak can be obtained and the phase of the reflected wave is 90 degrees away from the direct wave, the phase of the C / A code replica signal is controlled with a wide spacing to obtain the correlation peak. Switch to.

  The multipath error reduction unit 110 includes a phase control tracking processing unit 1102. The phase control tracking processing unit 1102 is connected to the switching unit 108. The phase control tracking processing unit 1102 detects a correlation peak by obtaining a correlation between the intermediate frequency signal to be input by the switching unit 108 and the C / A code replica signal. When detecting the correlation peak, the phase control of the C / A code replica signal is performed with a wide spacing. For example, the phase control tracking processing unit 1102 performs phase control of a C / A code replica signal by spacing with one chip, and obtains a correlation peak. The one chip is an example and can be changed as appropriate. The phase control tracking processing unit 1102 inputs the correlation peak to the pseudo distance calculation unit 114 and the switching determination unit 112.

  The multipath error reduction unit 110 includes a multipath reduction unit 1104. The multipath reduction unit 1104 is connected to the switching unit 108. The multipath reduction unit 1104 detects a correlation peak by obtaining a correlation between the intermediate frequency signal to be input by the switching unit 108 and the C / A code replica signal. When detecting the correlation peak, phase control (tracking) of the replica signal of the C / A code is performed with narrow spacing. For example, the multipath reduction unit 1104 performs phase control of the C / A code replica signal by spacing with 0.1 chip, and obtains a correlation peak. The 0.1 chip is an example and can be changed as appropriate. A spacing narrower than the spacing used by the phase control tracking processor 1102 is used. The multipath reduction unit 1104 inputs the signal intensity level of the correlation peak to the pseudo distance calculation unit 114. Further, the multipath reduction unit 1104 switches between the signal intensity level of the correlation peak and a predetermined correlation value obtained when obtaining the correlation between the received signal and the replica signal of the C / A code. To enter. For example, a predetermined correlation value obtained when obtaining a correlation between a received signal and a C / A code replica signal may be a correlation value corresponding to chips at both ends of a wide spacing. For example, in the case of 1-chip spacing, 0.5E and 0.5L may be used. Since the phase control of the C / A code replica signal is performed by the wide spacing before the phase control of the C / A code replica signal by the narrow spacing, the correlation corresponding to the chips at both ends of the wide spacing A value can be used. In the present embodiment, as an example, a case where 0.5E and 0.5L are input to the switching determination unit 112 will be described.

  The GNSS receiver 100 includes a switching determination unit 112. The switching determination unit 112 is connected to the multipath error reduction unit 110 and the switching unit 108. Based on the signal intensity level of the correlation peak to be input by the multipath error reduction unit 110, the switching determination unit 112 determines to the switching unit 108 when the signal intensity level of the correlation peak is greater than or equal to a predetermined correlation value threshold. The multipath reduction unit 1104 is instructed to input an intermediate frequency signal. Further, the signal strength level determination unit 112 determines whether the received signal is multi-based based on the difference between 0.5E and 0.5L based on 0.5E and 0.5L to be input by the multipath error reduction unit 110. Determine if it is affected by a path. For example, when the difference between 0.5E and 0.5L is greater than or equal to a predetermined correlation value difference threshold, it is determined that the multipath is affected.

  FIG. 9 shows the correlation values (0.5E, 0.5L) between the received signal and the C / A code replica signal when the moving body is traveling normally and when traveling at a low speed or when it is stopped. Shows time change.

  The received signal includes a direct wave and a reflected wave. The correlation value is normalized with the correlation peak. According to FIG. 9, when the direct wave and the reflected wave are included in the received signal, a magnitude switching between 0.5E and 0.5L can be seen regardless of the speed of the moving body. Further, the difference between 0.5E and 0.5L is smaller when the moving body is traveling normally than when the moving body is traveling at low speed or stopped. In addition, since 0.5E and 0.5L are closer when the moving body is traveling normally than when the moving body is traveling at low speed or stopped, 0.5E and 0.5L The number of switching between large and small increases. This is because the correlation value is time-averaged when the moving body is traveling normally.

  For example, when the difference between 0.5E and 0.5L is equal to or greater than a predetermined correlation value difference threshold, the switching determination unit 112 determines that the influence is due to multipath. As shown in FIGS. 4 and 5, the difference between 0.5E and 0.5L becomes larger when receiving the influence of multipath.

  Furthermore, the switching determination unit 112 calculates the number of switching times between 0.5E and 0.5L during a certain predetermined period. When the number of times of switching is less than a predetermined number of times of switching, it is determined that the moving body is traveling at a low speed or stopped. Further, when the number of times of switching is equal to or greater than a predetermined number of times of switching, it is determined that the moving body is traveling normally. As shown in FIG. 9, the number of times of switching between 0.5E and 0.5L during a predetermined period when the vehicle is running at a low speed or stopped is smaller than when the vehicle is running normally. It is.

  Further, the switching determination unit 112 calculates a difference between 0.5E and 0.5L during a certain predetermined period. When the difference is equal to or greater than a preset correlation value difference threshold, it may be determined that the multipath is affected. Further, when the difference is less than a preset correlation value difference threshold, it may be determined that the influence is not influenced by the multipath or the influence is small. Furthermore, when the number of times that the difference is equal to or greater than a preset correlation value difference threshold value is equal to or greater than a preset count threshold value, it may be determined that the vehicle is running at low speed or stopped. Further, when the number of times that the difference is equal to or greater than a preset correlation value difference threshold is less than the preset number of times threshold, it may be determined that the vehicle is traveling normally.

  When the switching determination unit 112 determines that the received signal is affected by multipath, and further determines that the moving body is traveling at low speed or stopped, the signal strength level of the correlation value is obtained by fading the reflected wave. Is determined to be at a level that cannot be phase controlled due to narrow spacing, in other words, whether or not it can be continued for a predetermined time. For example, based on the difference between 0.5E and 0.5L, the switching determination unit 112 determines whether the phase of the correlation value signal intensity level cannot be controlled due to narrow spacing based on whether the difference is maximized. Determine if it is likely to be. Specifically, as shown in FIG. 9, it is assumed that the phase of the reflected wave becomes 90 degrees when the signal intensity level of the correlation value becomes a level that cannot be controlled by the narrow spacing. The phase of the reflected wave becomes 90 degrees when 0.5E <0.5L and 0.5E = 0.5L. Before 0.5E = 0.5L from the state of 0.5E <0.5L, the difference between 0.5E and 0.5L becomes maximum. Accordingly, when the difference between 0.5E and 0.5L is maximized, the switching determination unit 112 determines that the signal intensity level of the correlation value is likely to become a signal intensity level that cannot be phase controlled due to narrow spacing. .

  When it is determined that the signal intensity level of the correlation value is likely to become a level that cannot be phase-controlled due to narrow spacing, the switching determination unit 112 determines that the signal intensity level of the correlation value becomes a level that cannot be phase-controlled due to narrow spacing. The switching unit 108 is instructed to input the intermediate frequency signal to the phase control tracking processing unit 1102.

  After instructing the switching unit 108 to input the intermediate frequency signal to the phase control tracking processing unit 1102, the switching determination unit 112 is based on the signal intensity level of the correlation peak to be input by the multipath error reduction unit 110. When the signal intensity level of the correlation peak is equal to or higher than a predetermined correlation value threshold, the switching unit 108 is instructed to input the intermediate frequency signal to the multipath reduction unit 1104.

<Switching determination unit>
The switching determination unit 112 includes a signal strength level determination unit 1122. The signal strength level determination unit 1122 switches based on the signal strength level of the correlation peak to be input by the multipath error reduction unit 110 when the signal strength level of the correlation peak is equal to or higher than a predetermined correlation value threshold. The unit 108 is instructed to input a signal of an intermediate frequency to the multipath reduction unit 1104. For example, when the signal intensity level of the correlation peak input by the phase control tracking processing unit 1102 is equal to or higher than a predetermined correlation value threshold, the signal strength level determination unit 1122 is connected to the multipath reduction unit 1104 in the switching unit 108 and in the middle. Instructs to input frequency signal. This is because, when the signal intensity level of the correlation peak input by the phase control tracking processing unit 1102 is equal to or higher than a predetermined correlation value threshold, it is determined that the correlation peak can be obtained by narrow spacing. Further, the signal strength level determination unit 1122 inputs 0.5E and 0.5L to be input by the multipath error reduction unit 110 to the multipath determination unit 1124. For example, the signal strength level determination unit 1122 inputs 0.5E and 0.5L to be input by the multipath reduction unit 1104 to the multipath determination unit 1124.

  The switching determination unit 112 includes a multipath determination unit 1124. The multipath determination unit 1124 is connected to the signal strength level determination unit 1122. The multipath determination unit 1124 is configured to input the multipath signal based on the difference between 0.5E and 0.5L based on 0.5E and 0.5L to be input by the signal strength level determination unit 1122. Determine if affected. The result of determination as to whether or not it is affected by multipath is input to the phase control determination unit 1126. In addition, the multipath determination unit 1124 inputs 0.5E and 0.5L input by the signal strength level determination unit 1122 to the phase control determination unit 1126. For example, the multipath determination unit 1124 determines that the received signal has a multipath effect based on the difference between 0.5E and 0.5L based on 0.5E and 0.5L detected by the multipath reduction unit 1104. Determine whether you have received.

  The switching determination unit 112 includes a phase control determination unit 1126. The phase control determination unit 1126 is connected to the multipath determination unit 1124. The phase control determination unit 1126 uses 0.5E and 0.5L to be input by the multipath determination unit 1124 when the multipath determination unit 1124 determines that the multipath determination unit 1124 is affected by the multipath. Calculate the number of switching times between 0.5E and 0.5L during a given period. The phase control determination unit 1126 determines that the moving body is traveling at a low speed or stopped when the number of times is less than a predetermined switching number threshold. Further, the phase control determination unit 1126 determines that the moving body is traveling normally when the number of times is equal to or greater than a predetermined switching number threshold. A determination result as to whether the moving body is traveling at a low speed or stopped is input to the timing control unit 1128.

  The switching determination unit 112 includes a timing control unit 1128. The timing control unit 1128 is connected to the phase control determination unit 1126. When the phase control determination unit 1126 determines that the moving body is traveling at low speed or is stopped, the timing control unit 1128 performs C / A by spacing with a narrow correlation value signal intensity due to reflected wave fading. It is determined whether or not the code replica signal is likely to be at a level where phase control cannot be performed. When it is determined that the signal intensity level of the correlation value is likely to become a level at which the phase control of the C / A code cannot be performed due to the narrow spacing, the timing control unit 1128 causes the replica signal of the C / A code due to the narrow spacing. Before the phase control becomes impossible, the switching unit 108 is instructed to input the intermediate frequency signal to the phase control tracking processing unit 1102.

  The GNSS receiver 100 includes a pseudo distance calculation unit 114. The pseudo distance calculation unit 114 is connected to the multipath error reduction unit 110. The pseudo distance calculation unit 114 calculates a pseudo distance based on the correlation peak to be input by the multipath error reduction unit 110. For example, the pseudo distance calculation unit 114 calculates the pseudo distance by calculating the phase delay amount of the correlation peak. The pseudo distance calculation unit 114 inputs the pseudo distance to the positioning calculation unit 116.

  The GNSS receiver 100 includes a positioning calculation unit 116. The positioning calculation unit 116 is connected to the pseudo distance calculation unit 114. The positioning calculation unit 116 calculates the current position of the GNSS satellite in the world coordinate system based on the satellite orbit information included in the navigation message. Since the GNSS satellite is one of artificial satellites, its movement is limited to a certain plane (orbital plane) including the center of gravity of the earth. The orbit of the GNSS satellite is an elliptical motion with the earth's center of gravity as one focal point, and the position of the GNSS satellite on the orbital plane can be calculated by sequentially calculating the Kepler equation. In addition, the position of the GNSS satellite shall be converted to a three-dimensional rotational coordinate from the position of the GNSS satellite on the orbital plane in consideration of the rotational relationship between the orbital plane of the GNSS satellite and the equatorial plane of the world coordinate system. It is obtained with. The world coordinate system is defined by an X axis and a Y axis that are orthogonal to each other in the equator plane, and a Z axis that is orthogonal to both the X axis and the Y axis, with the center of gravity of the earth as the origin.

  The positioning calculation unit 116 measures the position of the GNSS receiver 100 based on the calculation result of the satellite position and the calculation result of the pseudo distance input by the pseudo distance calculation unit 114. The position of the GNSS receiver 100 may be derived on the principle of triangulation using the respective satellite pseudoranges and satellite positions obtained for the three GNSS satellites 100. When derived from the principle of triangulation, the satellite pseudorange includes a clock error, so the clock error component is removed using the satellite pseudorange and the satellite position obtained for the fourth GNSS satellite. The positioning calculation unit 110 outputs the current position.

  The positioning method of the position of the GNSS satellite is not limited to such independent positioning, but may be interference positioning (a method in which received data at a fixed station installed at a known point is used in combination). In the case of interference positioning, the position of the GNSS receiver 100 is measured using a single phase difference, a double phase difference, or the like of pseudoranges obtained by the fixed station and the GNSS receiver 100, respectively.

<Operation of this GNSS receiver>
FIG. 10 shows the operation of the GNSS receiver 100.

  The GNSS receiver 100 determines whether or not satellite acquisition is completed (step S1002). For example, the radio wave transmitted by the GNSS satellite is input to the high frequency processing unit 104 via the antenna 102. The high frequency processing unit 104 converts the high frequency signal from the antenna 102 into an intermediate frequency signal. The intermediate frequency signal is input to the satellite acquisition unit 106, and the satellite acquisition unit 106 acquires a GNSS satellite based on the intermediate frequency signal.

  The GNSS receiver 100 obtains a correlation between the positioning signal from the GNSS satellite captured in step S1002 and the C / A code replica signal (step S1004). This GNSS receiver 100 performs phase control so that the signal intensity levels of the correlation values at both ends of the spacing are equal to each other by wide spacing. For example, the switching unit 108 inputs a signal to be input by the satellite capturing unit 106 to the phase control tracking processing unit 1102 immediately after the GNSS receiver 100 is activated. The phase control tracking processing unit 1102 obtains a correlation between the input signal and the C / A code replica signal. The phase control tracking processing unit 1102 performs phase control of the C / A code replica signal with wide spacing. For example, the phase control is performed so that the signal intensity levels of the correlation values at both ends of the wide spacing are equal. For example, phase control is performed so that the signal intensity levels (0.5E, 0.5L) of the correlation values at both ends of the spacing by one chip are equal.

  The GNSS receiver 100 controls the phase so that the correlation value of the center chip between the chip corresponding to 0.5E and the chip corresponding to 0.5L takes a maximum value. The GNSS receiver 100 determines whether 0.5E and 0.5L are equal values, and whether the maximum value (correlation peak) P is larger than 0.5E and 0.5L (step S1006). For example, the phase control tracking processing unit 1102 performs phase control so that the signal intensity levels of the correlation values at both ends of the spacing by one chip are equal, and the tracking point in the middle of the spacing is maximized. Adjust the phase of the C / A code replica signal. The phase control tracking processing unit 1102 has the same signal intensity level of the correlation value at both ends of the spacing by one chip (0.5E = 0.5L), and the correlation peak P that is the maximum value of the tracking point is 0.5E, Determine whether the value is greater than 0.5L (P> 0.5E, P> 0.5L).

  When it is determined that the signal intensity levels of the correlation values at both ends of the spacing by one chip are equal and the correlation peak P, which is the maximum value of the tracking point, is a value larger than 0.5E and 0.5L (step S1006) : YES), the GNSS receiver 100 determines whether or not the signal intensity level of the correlation peak P is equal to or higher than the correlation value threshold (step S1008). For example, the phase control tracking processing unit 1102 inputs the signal intensity level of the correlation peak P to the switching determination unit 112. The signal strength level determination unit 1124 of the switching determination unit 112 determines whether the signal strength level of the correlation peak P input by the phase control tracking processing unit 1102 is equal to or higher than the correlation value threshold. By determining whether or not the signal intensity level of the correlation peak P is equal to or higher than the correlation value threshold value, it is determined whether or not the phase control of the C / A code replica signal can be performed with narrow spacing.

  On the other hand, it is determined in step S1006 that the signal intensity levels of the correlation values at both ends of the spacing by one chip are equal, and the correlation peak P, which is the maximum value of the tracking point, is larger than 0.5E and 0.5L. If not determined (step S1006: NO), the GNSS receiver 100 determines whether or not a timeout has occurred (step S1010). For example, the phase control tracking processing unit 1102 determines whether a timeout has occurred.

  If it is not determined that timeout has occurred (step S1010: NO), the process returns to step S1004. The phase control tracking processing unit 1102 performs processing for obtaining a correlation between the positioning signal from the GNSS satellite captured in step S1002 and the C / A code replica signal until time-out, and both ends of spacing by one chip. The process of determining whether or not the correlation intensity P of the correlation value is equal and the correlation peak P, which is the maximum value of the tracking point, is larger than 0.5E and 0.5L is continued. In other words, tracking is continued.

  If it is determined that a timeout has occurred (step S1010: YES), the process returns to step S1002. If time-out occurs, it is determined that satellite tracking is impossible, and the operation is performed again after capturing the satellite. For example, the satellite capturing unit 106 performs satellite capture based on a signal from a GNSS satellite. When it is determined to start from satellite acquisition based on the signal from the GNSS satellite, for example, the switching determination unit 112 instructs the switching unit 108 to instruct the satellite acquisition unit 106 to perform satellite acquisition again (hereinafter, referred to as the following). (Referred to as “satellite reacquisition command”). The switching unit 108 inputs a satellite re-acquisition command to the satellite capturing unit 106 according to the command from the switching determination unit 112. The satellite acquisition unit 106 performs satellite acquisition again according to the satellite re-acquisition command input by the switching unit 108.

  When it is determined in step S1008 that the correlation peak P is equal to or greater than the correlation value threshold (step S1008: YES), the GNSS receiver 100 performs phase control of the C / A code replica signal with narrow spacing. . For example, phase control is performed so that the signal intensity levels of the correlation values at both ends of the narrow spacing are equal (step S1012). For example, the phase control is performed so that the signal intensity levels (NE, NL) of the correlation values at both ends of the spacing by 0.1 chip are equal. By controlling the phase so that the signal strength levels of the correlation values at both ends of the narrow spacing are equal, the signal strength level (NE of the correlation value at the chip closer to the chip corresponding to the correlation peak obtained by the spacing by one chip. , NL). For example, when the signal intensity level determination unit 1122 determines that the signal intensity level of the correlation peak P input by the phase control tracking processing unit 1102 is equal to or higher than the correlation value threshold, the signal acquisition level is input to the switching unit 108 by the satellite capturing unit 106. The multipath reduction unit 1104 is instructed to input a signal to be processed. As a result of the instruction, a signal from the satellite acquisition unit 106 is input to the multipath reduction unit 1104. The multipath reduction unit 1104 obtains a correlation between the input signal and the C / A code replica signal. The multipath reduction unit 1104 controls the phase of the C / A code replica signal with narrow spacing. For example, the phase control is performed so that the signal intensity levels (NE, NL) of the correlation values at both ends of the spacing by 0.1 chip are equal. Phase control is performed so that NE and NL are equal, and the phase of the C / A code replica signal is adjusted so that the tracking point in the middle of the spacing is maximized.

  The GNSS receiver 100 determines whether or not the signal intensity level of the correlation peak P is greater than or equal to the correlation value threshold (step S1014). For example, the multipath reduction unit 1104 inputs the signal intensity level of the correlation peak P to the signal intensity level determination unit 1122. The signal strength level determination unit 11022 determines whether the signal strength level of the correlation peak P input by the multipath reduction unit 1104 is greater than or equal to the correlation value threshold value.

  When it is determined that the signal intensity level of the correlation peak P is equal to or higher than the correlation value threshold (step S1014: YES), the GNSS receiver 100 determines whether the received signal is affected by multipath (step S1014). S1016). For example, the multipath determination unit 1124 determines that the received signal is multipath based on the difference between 0.5E and 0.5L based on 0.5E and 0.5L to be input by the signal strength level determination unit 1102. It is determined whether it is affected by. On the other hand, when it is not determined that the signal intensity level of the correlation peak P is equal to or higher than the correlation value threshold (step S1014: NO), the process returns to step S1004. The GNSS receiver 100 determines that the phase control of the C / A code replica signal cannot be performed with a narrow spacing, and performs the phase control of the C / A code replica signal with a wide spacing. The process returns to S1004.

  If it is determined in step S1016 that the signal is affected by multipath (step S1016: YES), the GNSS receiver 100 uses the phase of the replica signal of the C / A code due to the narrowing of the correlation signal strength level. It is determined whether or not the signal intensity level that cannot be controlled is likely to be reached (step S1018). In other words, it is determined whether or not the phase control of the C / A code replica signal cannot be performed by the narrow spacing due to the fading of the reflected wave. For example, the phase control determination unit 1126 calculates the number of times of switching between 0.5E and 0.5L during a certain predetermined time, and when the number of times is less than a predetermined switching number threshold, fading of the reflected wave Therefore, it is determined that the phase control of the C / A code replica signal cannot be performed due to narrower spacing. This is because it is determined that the moving body is traveling at a low speed or stopped. On the other hand, if it is determined in step S1016 that there is no influence of multipath (step S1016: NO), the process returns to step S1012. When it is determined that there is no influence of multipath, there is no influence due to the fading of the reflected wave, so that the phase control of the C / A code replica signal can be performed with a narrow spacing. Since the phase control of the C / A code replica signal can be performed by narrow spacing, the process returns to step S1012.

  When it is determined that the signal intensity level of the correlation value is likely to become a signal intensity level at which the phase control of the replica signal of the C / A code cannot be performed due to the narrow spacing (step S1018: YES), the GNSS receiving apparatus 100 Then, it is determined whether or not the signal intensity level of the correlation value is likely to become a signal intensity level at which the phase control of the replica signal of the C / A code cannot be performed due to the fading of the reflected wave (step S1020). For example, the timing control unit 1128 controls the phase of the replica signal of the C / A code based on whether or not the difference between 0.5E and 0.5L is maximized by the spacing with a narrow signal intensity level of the correlation value. It is determined whether or not a signal intensity level that cannot be performed is likely to be obtained. On the other hand, when it is not determined that the signal intensity level of the correlation value is likely to become a signal intensity level at which the phase control of the C / A code replica signal cannot be performed due to the narrow spacing (step S1018: NO), the process returns to step S1012. . If it is determined that the signal intensity level of the correlation value is not likely to result in a signal intensity level where the phase control of the C / A code replica signal cannot be performed due to the narrow spacing, the phase control may be performed with the narrow spacing. This is because it is preferable.

  When it is determined that the signal intensity level of the correlation value is likely to become a signal intensity level at which the phase control of the C / A code replica signal cannot be performed due to the narrow spacing (step S1020: YES), the process returns to step S1004. This GNSS receiver 100 performs phase control of a C / A code replica signal by wide spacing before reaching a signal intensity level at which phase control of the C / A code replica signal cannot be performed by narrow spacing. Switch as follows. For example, the timing control unit 1128 sets the switching unit 108 to the phase control tracking processing unit 1102 to the intermediate frequency before the signal intensity level at which the phase control of the C / A code replica signal cannot be performed due to the narrow spacing. Instruct to input signal. On the other hand, if it is not determined that the signal intensity level of the correlation value is likely to become a signal intensity level that cannot be phase-controlled due to narrow spacing (step S1020: NO), the process returns to step S1012. If it is determined that the signal intensity level of the correlation value is not likely to result in a signal intensity level where the phase control of the C / A code replica signal cannot be performed due to the narrow spacing, the phase control may be performed with the narrow spacing. This is because it is preferable.

  In the flowchart shown in FIG. 10, the processing for mainly obtaining the correlation peak has been described. However, the positioning calculation is also performed in parallel with the processing for obtaining the correlation peak.

  For example, in step S1006, it is determined that the signal intensity levels of the correlation values at both ends of the spacing by one chip are equal and the correlation peak P, which is the maximum value of the tracking point, is larger than 0.5E and 0.5L. When it is determined (step S1006: YES), the phase control tracking processing unit 1102 inputs the correlation peak to the pseudo-range calculating unit 114. The pseudo distance calculation unit 114 obtains a pseudo distance based on the correlation peak input by the phase control tracking processing unit 1102. The pseudo distance is input to the positioning calculation unit 116. The positioning calculation unit 116 measures the position of the GNSS receiver 100 based on the calculation result of the satellite position and the calculation result of the pseudo distance input by the pseudo distance calculation unit 114.

  For example, when it is determined in step S1014 whether the signal intensity level of the correlation peak P is equal to or higher than the correlation value threshold, the multipath reduction unit 1104 inputs the correlation peak P to the pseudo distance calculation unit 114. The pseudo distance calculation unit 114 obtains a pseudo distance based on the correlation peak input by the multipath reduction unit 1104. The pseudo distance is input to the positioning calculation unit 116. The positioning calculation unit 116 measures the position of the GNSS receiver 100 based on the calculation result of the satellite position and the calculation result of the pseudo distance input by the pseudo distance calculation unit 114.

  In this embodiment, the signal strength level determination unit 1122 may determine whether the signal strength level of a predetermined correlation value is greater than the correlation value threshold when correlation detection is performed with a wide spacing. Good. For example, it may be determined whether the signal strength level of the correlation value at both ends of the wide spacing is greater than the correlation value threshold. The correlation value may be different from a correlation value threshold used for determining the correlation peak. When determining the signal strength levels of the correlation values at both ends of the wide spacing, the phase control tracking processing unit 1102 inputs the signal strength levels of the correlation values at both ends of the wide spacing to the signal strength level determining unit 1122.

  Further, the signal strength level determination unit 1122 may determine whether or not the signal strength level of a predetermined correlation value is greater than the correlation value threshold when the correlation detection is performed with narrow spacing. It may be determined whether the signal strength level of the correlation value at both ends of the wide spacing or the narrow spacing is greater than the correlation value threshold. The correlation value may be different from the correlation value threshold used for determination of the correlation peak in step S1014. When determining the signal strength level of the correlation value at both ends of the wide spacing or the narrow spacing, the multipath reduction unit 1104 sends the signal of the correlation value at both ends of the wide spacing or the narrow spacing to the signal strength level determination unit 112. Enter the intensity level.

  Further, the signal strength level determination unit 1122 may determine the signal strength level of the real-time correlation value. Further, the signal strength level determination unit 1122 calculates the average value of the correlation values input by the phase control tracking processing unit 1102 or the multipath reduction unit 1104 at a certain time interval, and whether the average value is larger than the correlation value threshold value. You may make it determine whether. In addition, the signal strength determination unit 112 integrates the correlation values input by the phase control tracking processing unit 1102 or the multipath reduction unit 1104 at a certain time interval, and determines whether the integration value is larger than the correlation value threshold value. You may do it.

According to the present embodiment, based on the signal strength level of the correlation value, it is determined whether or not the phase control of the C / A code replica signal can be performed with a narrow spacing of the signal strength level of the correlation value. It is determined whether or not it is equal to or greater than the correlation value threshold value. When it is determined that the signal strength level of the correlation value is less than the correlation value threshold, it is determined that the phase control of the C / A code replica signal cannot be performed due to the narrow spacing, and the wide spacing is used. Switch to correlation peak detection. Further, based on the signal intensity level of the correlation value, it is determined whether the received signal is affected by multipath. When it is determined that the vehicle is affected by the multipath, it is determined whether the moving body is traveling at a low speed or stopped. If it is determined that the moving body is traveling at low speed or stopped, whether the signal strength level of the correlation value is likely to become a signal strength level that cannot be used for phase control of the C / A code replica signal due to narrow spacing. Determined. If it is determined that the signal intensity level of the correlation value is such that the phase of the replica signal of the C / A code cannot be controlled due to the narrow spacing, the signal intensity of the correlation value is determined by fading of the reflected wave. It is determined whether the signal strength level is likely to be such that the phase control of the C / A code replica signal cannot be performed due to the narrow spacing. If it is determined that the signal intensity level of the correlation value is likely to result in a signal intensity level where the phase control of the replica signal of the C / A code cannot be performed due to the narrow spacing, the replica signal of the C / A code due to the narrow spacing Before reaching a signal intensity level at which phase control of the C / A code cannot be performed, switching to a process of performing phase control of the C / A code replica signal by wide spacing. With the above processing, positioning can be continued without removing the satellite tracking even when a signal affected by multipath is received when the moving body is traveling at low speed or stopped. Since positioning can be continued, the positioning rate can be improved.
<Modification>
<GNSS receiver>
The GNSS receiver 100 according to the present modification includes a selection unit 118 instead of the switching unit 108 in the GNSS reception device described with reference to FIG.

  FIG. 11 shows the GNSS receiver 100.

  In the present GNSS receiver 100, the satellite acquisition unit 106 is connected to the phase control tracking processing unit 1102 and the multipath reduction unit 1104. The satellite acquisition unit 106 inputs an intermediate frequency signal from the GNSS satellite captured by the GNSS receiver 100 to the phase control tracking processing unit 1102 and the multipath reduction unit 1104. Phase control tracking processing section 1102 and multipath reduction section 1104 are connected to selection section 118.

  In the GNSS receiver 100, the phase control tracking processing unit 1102 performs C / A with wide spacing while the multipath reduction unit 1104 performs phase control of the C / A code replica signal with narrow spacing. The process of controlling the phase of the code replica signal is continued.

  The phase control tracking processing unit 1102 detects a correlation peak by obtaining a correlation between the intermediate frequency signal to be input by the satellite capturing unit 106 and the C / A code replica signal. When detecting the correlation peak, the phase control of the C / A code replica signal is performed with a wide spacing. For example, the phase control tracking processing unit 1102 obtains a correlation peak by performing phase control of a C / A code replica signal by spacing with one chip. The one chip is an example and can be changed as appropriate. The phase control tracking processing unit 1102 inputs the correlation peak to the selection unit 118. In addition, the phase control tracking processing unit 1102 may input phase information obtained by performing phase control of the C / A code replica signal to the multipath reduction unit 1104. The phase information may include a phase of a correlation peak and a phase of a certain correlation value. By inputting the phase information obtained by controlling the phase of the C / A code replica signal, the multipath reduction unit 1104 uses the phase information to perform the C / A code replica signal with narrow spacing. Therefore, the correlation peak can be obtained more quickly.

  The multipath reduction unit 1104 detects a correlation peak by taking a correlation between an intermediate frequency signal to be input by the satellite acquisition unit 106 and a C / A code replica signal. When the correlation peak is detected, the phase of the C / A code replica signal is controlled by narrow spacing. For example, the multipath reduction unit 1104 obtains a correlation peak by performing phase control of a C / A code replica signal by spacing with 0.1 chip. The 0.1 chip is an example and can be changed as appropriate. A spacing narrower than the spacing used by the phase control tracking processor 1102 is used. The multipath reduction unit 1104 inputs the correlation peak to the selection unit 118. Further, the multipath reduction unit 1104 inputs the correlation peak and a predetermined correlation value obtained when obtaining the correlation between the received signal and the C / A code replica signal to the switching determination unit 112. For example, a predetermined correlation value obtained when obtaining a correlation between a received signal and a C / A code replica signal may be a correlation value corresponding to chips at both ends of a wide spacing. For example, in the case of 1-chip spacing, 0.5E and 0.5L may be used. Since the phase control of the C / A code replica signal is performed by the wide spacing before the phase control of the C / A code replica signal by the narrow spacing, the correlation corresponding to the chips at both ends of the wide spacing A value can be used. In the present embodiment, as an example, a case where 0.5E and 0.5L are input to the switching determination unit 112 will be described.

  Based on the signal strength level of the correlation peak to be input by the multipath error reduction unit 110, the signal strength level determination unit 1122 selects a selection unit when the correlation peak signal strength level is equal to or higher than a predetermined correlation value threshold. 118 is instructed to input the correlation peak to be output by the multipath reduction unit 1104 to the pseudo-range calculation unit 114. For example, when the signal intensity level of the correlation peak input by the phase control tracking processing unit 1102 is equal to or higher than a predetermined correlation value threshold, the signal intensity level determination unit 1122 sends the correlation value to the pseudo distance calculation unit 114 to the selection unit 118. Instructs you to enter a peak. When the signal intensity level of the correlation peak input by the phase control tracking processing unit 1102 is equal to or higher than a predetermined correlation value threshold, the phase control of the C / A code replica signal is performed by narrow spacing, and the correlation peak is This is because it is determined to be required.

  FIG. 12 shows an example of temporal variation of the correlation value of the correlation peak. FIG. 12 shows an example of setting a correlation value threshold value. The correlation value threshold is set based on whether or not the phase of the C / A code replica signal is controlled by narrow spacing and a correlation peak can be detected. The correlation peak is less likely to be detected as the correlation peak is lower. In the example shown in FIG. 12, the correlation value of the correlation peak gradually decreases with time, and gradually increases from a certain time. When the signal strength level determination unit 112 determines that the signal strength level of the correlation peak to be input by the phase control tracking processing unit 1102 or the multipath reduction unit 1104 is less than the correlation value threshold, the C / A is performed by wide spacing. The phase of the code replica signal is controlled to determine that a correlation peak should be detected. This is because it is assumed that phase control of a C / A code replica signal cannot be performed with narrow spacing. When the phase of the C / A code replica signal is controlled by wide spacing and it is determined that the correlation peak should be detected, the signal strength level determination unit 1122 is input to the selection unit 118 by the multipath reduction unit 1104 Instructs the pseudo-range calculator 114 to input the power correlation peak.

  Further, the signal strength level determination unit 1122 inputs 0.5E and 0.5L to be input by the multipath error reduction unit 110 to the multipath determination unit 1124.

  The multipath determination unit 1124 determines that the received signal is affected by the multipath based on the difference between 0.5E and 0.5L based on 0.5E and 0.5L to be input by the signal strength level determination unit 1122. Determine whether you have received. The result of determination as to whether or not it is affected by multipath is input to the phase control determination unit 1126. In addition, the multipath determination unit 1124 inputs 0.5E and 0.5L input by the signal strength level determination unit 1122 to the phase control determination unit 1126.

  The phase control determination unit 1126 uses 0.5E and 0.5L to be input by the multipath determination unit 1124 when the multipath determination unit 1124 determines that the multipath determination unit 1124 is affected by the multipath. Calculate the number of switching times between 0.5E and 0.5L during a given period. The phase control determination unit 1126 determines that the moving body is traveling at a low speed or stopped when the number of times is less than a predetermined switching number threshold. Further, the phase control determination unit 1126 determines that the moving body is traveling normally when the number of times is equal to or greater than a predetermined switching number threshold. A determination result as to whether the moving body is traveling at a low speed or stopped is input to the timing control unit 1128.

  When the phase control determination unit 1126 determines that the moving body is traveling at low speed or is stopped, the timing control unit 1128 causes the C / A code to be generated by the spacing of the correlation signal having a narrow signal intensity level due to fading of the reflected wave. It is determined whether or not the level of replica signal phase control is likely to be reached. When it is determined that the phase value of the C / A code replica signal is not likely to be controlled due to the narrowing of the correlation signal strength level, the timing control unit 1128 causes the C / A code to narrow down due to the narrow spacing. Immediately before reaching the level at which the phase control of the replica signal cannot be performed, the selection unit 118 is instructed to input the correlation peak to be input by the phase control tracking processing unit 1102 to the pseudo-range calculation unit 114.

  The pseudo distance calculation unit 114 calculates the pseudo distance based on the correlation peak to be input by the selection unit 118. For example, the pseudo distance calculation unit 114 calculates the pseudo distance by calculating the phase delay amount of the correlation peak. The pseudo distance calculation unit 114 inputs the pseudo distance to the positioning calculation unit 116.

  In this modification, the signal strength level determination unit 1122 may determine the signal strength level of the real-time correlation value. Further, the signal strength level determination unit 1122 calculates the average value of the correlation values input by the phase control tracking processing unit 1102 or the multipath reduction unit 1104 at a certain time interval, and whether the average value is larger than the correlation value threshold value. You may make it determine whether. In addition, the signal strength determination unit 112 integrates the correlation values input by the phase control tracking processing unit 1102 or the multipath reduction unit 1104 at a certain time interval, and determines whether the integration value is larger than the correlation value threshold value. You may do it.

  According to this modification, while the phase control of the C / A code replica signal is performed by the multipath reduction unit 1104 with narrow spacing, the phase control tracking processing unit 1102 performs C / A with wide spacing. Continue to control the phase of the code replica signal. Since the phase control tracking processing unit 1102 continues to control the phase of the C / A code replica signal with a wide spacing, in addition to the effects of the above-described embodiment, the timing control unit 1128 includes a C / A code with a narrow spacing. Instructing the selection unit 118 to input the correlation peak to be input by the phase control tracking processing unit 1102 to the pseudo-range calculation unit 114 immediately before the phase control of the A code replica signal becomes impossible. Can do. Since the instruction can be given immediately before the phase at which the phase control of the C / A code replica signal cannot be performed due to the narrow spacing, the multipath reduction unit 1104 has a longer time than the above-described embodiment, and the C / A due to the narrow spacing. By performing the phase control of the code replica signal, the processing for obtaining the correlation peak can be continued. Since the long-time multipath reduction unit 1104 performs phase control of the C / A code replica signal with narrow spacing, the process of obtaining the correlation peak can be continued. Therefore, the phase delay due to the correlation peak having a smaller error due to the reflected wave The amount can be calculated.

  According to the present embodiment, there is provided a GNSS receiver that performs a positioning calculation based on a positioning signal transmitted from a GNSS satellite.

The GNSS receiver is
A GNSS receiver that performs a positioning operation based on a positioning signal transmitted from a GNSS satellite,
A first correlation peak detection unit as a phase control tracking processing unit that detects a peak of a correlation value between the positioning signal and a C / A code replica signal;
A second correlation peak detection unit as a multipath reduction unit for detecting a peak of a correlation value between the positioning signal and the replica signal of the C / A code by a multipath error reduction technique;
A signal strength detection unit as a phase control tracking processing unit and a multipath reduction unit for detecting the signal strength of the positioning signal;
A switching unit that switches an input destination of the positioning signal between the first correlation peak detection unit and the second correlation peak detection unit;
The switching unit is instructed to input to the second correlation peak detection unit when the signal intensity is equal to or higher than a predetermined threshold, and when the signal intensity is lower than the predetermined threshold, the positioning signal is transmitted to the first A signal intensity level determination unit that gives an instruction to input to the correlation peak detection unit of
A multipath determination unit that determines whether the positioning signal is affected by a multipath based on a correlation value to be detected by the second correlation peak detection unit;
Based on the correlation value to be detected by the second correlation peak detection unit when the positioning signal is determined to be affected by the multipath by the multipath determination unit, the second correlation peak A phase control determination unit that determines whether or not the detection unit can continue to detect the peak of the correlation value;
A timing control unit that instructs the switching unit to input the positioning signal to the first correlation peak detection unit when it is determined by the phase control determination unit that it cannot be continued;
A pseudo distance calculating unit and a positioning for calculating a pseudo distance based on the correlation peak detected by the first correlation peak detecting unit or the second correlation peak detecting unit and calculating a position based on the pseudo distance And a positioning calculation unit as a calculation unit.

further,
The first correlation peak detection unit detects a peak of a correlation value between the positioning signal and a C / A code replica signal based on a first phase interval;
The second correlation peak detection unit detects a peak of a correlation value between the positioning signal and the C / A code replica signal based on a second phase interval narrower than the first phase interval.

  Positioning can be continued without removing the satellite tracking even when a signal affected by multipath is received when the moving body is traveling at low speed or stopped. Since positioning can be continued, the positioning rate can be improved.

further,
The positioning signal includes a direct wave and a reflected wave,
The timing control unit determines that the phase control determination unit can continue to detect a correlation value peak between the positioning signal and the C / A code replica signal by the multipath error reduction technique for a predetermined time. If not, the switching unit is instructed to input the positioning signal to the first correlation peak detection unit at a timing when the phase of the reflected wave is shifted by 90 degrees with respect to the direct wave.

  If it is not determined that the peak of the correlation value between the positioning signal and the C / A code replica signal can be continued for a predetermined time by the multipath error reduction technology, the positioning signal and C are detected by the multipath error reduction technology. While the correlation value peak with the / A code replica signal can be detected, it is possible to switch to the first correlation peak detection unit.

further,
The multipath determination unit determines whether the positioning signal is affected by multipath based on a difference between two correlation values detected by the second correlation peak detection unit.

  Based on the difference between the two correlation values detected by the second correlation peak detector, if the difference is equal to or greater than a preset correlation value difference threshold, it is determined that the multipath is affected, When the difference is less than a preset correlation value difference threshold, it is determined that the multipath is not affected.

further,
Based on the number of times the sign of the difference between the two correlation values detected by the second correlation peak detection unit is switched, the phase control determination unit uses the multipath error reduction technique to detect the positioning signal and the C / A code. It is determined whether or not the peak of the correlation value with the replica signal can be continued for a predetermined time.

  Based on the number of times the sign of the difference between the two correlation values detected by the second correlation peak detection unit is switched, the moving body is running at a low speed or stopped when the number of times of switching is less than a predetermined switching frequency threshold. If the number of times of switching is equal to or greater than a predetermined number of times of switching, it is determined that the moving body is traveling normally.

further,
The multipath error reduction technique includes any one of a narrow correlator, an early slope, a strobe correlator, and a multipath estimation delay lock loop.

  The effect of multipath can be reduced by any one of a narrow correlator, an early slope, a strobe correlator, and a multipath estimation delay lock loop.

  According to the present embodiment, there is provided a positioning method in a GNSS receiver that performs a positioning calculation based on a positioning signal transmitted from a GNSS satellite.

The positioning method is
A positioning method in a GNSS receiver that performs a positioning operation based on a positioning signal transmitted from a GNSS satellite,
A first correlation peak detecting step for detecting a peak of a correlation value between the positioning signal and a C / A code replica signal;
A second correlation peak detecting step for detecting a peak of a correlation value between the positioning signal and the C / A code replica signal by a multipath error reduction technique;
A signal strength detection step of detecting a signal strength of the positioning signal;
A switching step of switching between the first correlation peak detection step and the second correlation peak detection step;
A signal strength level determination step that switches to the second correlation peak detection step when the signal strength is equal to or greater than a predetermined threshold, and that switches to the first correlation peak detection step when the signal strength is less than the predetermined threshold;
A multipath determination step of determining whether or not the positioning signal is affected by a multipath based on the correlation value to be detected by the second correlation peak detection step;
When it is determined in the multipath determination step that the positioning signal is affected by the multipath, the second correlation peak is determined based on the correlation value to be detected in the second correlation peak detection step. A phase control determination step for determining whether the detection step can continue to detect the peak of the correlation value;
A timing control step for instructing to switch to the first correlation peak detection step when it is determined that the phase control determination step cannot continue,
A positioning calculation step of calculating a pseudo distance based on the correlation peak detected by the first correlation peak detection step or the second correlation peak detection step and calculating a position based on the pseudo distance. .

  Although the present invention has been described above with reference to specific embodiments, each embodiment is merely an example, and those skilled in the art will understand various variations, modifications, alternatives, substitutions, and the like. I will. For convenience of explanation, an apparatus according to an embodiment of the present invention has been described using a functional block diagram, but such an apparatus may be implemented in hardware, software, or a combination thereof. The present invention is not limited to the above-described embodiments, and various variations, modifications, alternatives, substitutions, and the like are included without departing from the spirit of the present invention.

2 High Frequency Processing Unit 4 Satellite Acquisition Unit 6 Correlator Unit 8 Pseudo Distance Calculation Unit 10 GNSS Receiver 100 GNSS Receiver 102 Antenna 104 High Frequency Processing Unit 106 Satellite Acquisition Unit 108 Switching Unit 110 Multipath Error Reduction Unit 1102 Phase Control Tracking Processing Unit 1104 Multipath reduction unit 112 Switching determination unit 1122 Signal strength level determination unit 1124 Multipath determination unit 1126 Phase control determination unit 1128 Timing control unit 114 Pseudo distance calculation unit 116 Positioning calculation unit 118 Selection unit

Claims (7)

A GNSS receiver that performs a positioning operation based on a positioning signal transmitted from a GNSS satellite,
A first correlation peak detector for detecting a peak of a correlation value between the positioning signal and a C / A code replica signal;
A second correlation peak detector for detecting a peak of a correlation value between the positioning signal and the C / A code replica signal by a multipath error reduction technique;
A signal strength detector for detecting the signal strength of the positioning signal;
A switching unit that switches an input destination of the positioning signal between the first correlation peak detection unit and the second correlation peak detection unit;
The switching unit is instructed to input to the second correlation peak detection unit when the signal intensity is equal to or higher than a predetermined threshold, and when the signal intensity is lower than the predetermined threshold, the positioning signal is transmitted to the first A signal intensity level determination unit that gives an instruction to input to the correlation peak detection unit of
A multipath determination unit that determines whether the positioning signal is affected by a multipath based on a correlation value to be detected by the second correlation peak detection unit;
Based on the correlation value to be detected by the second correlation peak detection unit when the positioning signal is determined to be affected by the multipath by the multipath determination unit, the second correlation peak A phase control determination unit that determines whether or not the detection unit can continue to detect the peak of the correlation value;
A timing control unit that instructs the switching unit to input the positioning signal to the first correlation peak detection unit when it is determined by the phase control determination unit that it cannot be continued;
A positioning calculation unit that calculates a pseudo distance based on the correlation peak detected by the first correlation peak detection unit or the second correlation peak detection unit, and calculates a position based on the pseudo distance. GNSS receiver. In the GNSS receiver according to claim 1,
The first correlation peak detection unit detects a peak of a correlation value between the positioning signal and a C / A code replica signal based on a first phase interval;
The second correlation peak detector detects a correlation value peak between the positioning signal and a C / A code replica signal at a second phase interval narrower than the first phase interval. . In the GNSS receiver according to claim 1 or 2,
The positioning signal includes a direct wave and a reflected wave,
The timing control unit determines that the phase control determination unit can continue to detect a correlation value peak between the positioning signal and the C / A code replica signal by the multipath error reduction technique for a predetermined time. If not, a GNSS receiver that instructs the switching unit to input the positioning signal to the first correlation peak detection unit at a timing when the phase of the reflected wave is shifted by 90 degrees with respect to the direct wave. In the GNSS receiver according to any one of claims 1 to 3,
The multipath determination unit is a GNSS receiver that determines whether the positioning signal is affected by a multipath based on a difference between two correlation values detected by the second correlation peak detection unit. In the GNSS receiver according to any one of claims 1 to 3,
Based on the number of times the sign of the difference between the two correlation values detected by the second correlation peak detection unit is switched, the phase control determination unit uses the multipath error reduction technique to detect the positioning signal and the C / A code. A GNSS receiver that determines whether or not a peak of a correlation value with a replica signal can be continued for a predetermined time. In the GNSS receiver according to claim 1,
The multipath error reduction technique includes a narrow correlator, an early slope, a strobe correlator, and a multipath estimation delay lock loop. A positioning method in a GNSS receiver that performs a positioning operation based on a positioning signal transmitted from a GNSS satellite,
A first correlation peak detecting step for detecting a peak of a correlation value between the positioning signal and a C / A code replica signal;
A second correlation peak detecting step for detecting a peak of a correlation value between the positioning signal and the C / A code replica signal by a multipath error reduction technique;
A signal strength detection step of detecting a signal strength of the positioning signal;
A switching step of switching between the first correlation peak detection step and the second correlation peak detection step;
A signal strength level determination step that switches to the second correlation peak detection step when the signal strength is equal to or greater than a predetermined threshold, and that switches to the first correlation peak detection step when the signal strength is less than the predetermined threshold;
A multipath determination step of determining whether or not the positioning signal is affected by a multipath based on the correlation value to be detected by the second correlation peak detection step;
When it is determined in the multipath determination step that the positioning signal is affected by the multipath, the second correlation peak is determined based on the correlation value to be detected in the second correlation peak detection step. A phase control determination step for determining whether the detection step can continue to detect the peak of the correlation value;
A timing control step for instructing to switch to the first correlation peak detection step when it is determined that the phase control determination step cannot continue,
A positioning calculation step of calculating a pseudo distance based on the correlation peak detected by the first correlation peak detection step or the second correlation peak detection step and calculating a position based on the pseudo distance. Positioning method.

Images